powdermnky007 Posted June 10, 2004 Share Posted June 10, 2004 I just bought a mapltree ultra 4a preamp from Craig. On the unit it has two things in the middle that aren't tubes. If i was at home i would give a better description. you can see them in this picture: http://hollowstate.netfirms.com/ultra4.htm they each have a wire coming off the back of them that is connected to some sort of connector. It reminds me of how an fm antenna in your car looks like. What is this and what do I do with it!! LOL thanks guys as always =) -Justin Link to comment Share on other sites More sharing options...
NOSValves Posted June 10, 2004 Share Posted June 10, 2004 The wire is something I did as a tweak the two tubes your speaking of are 6SC7 metal envelop for a phono stage. I added the wires as a absolute ground to limit any noise pickup in my shop which is very electrically noisy you plug them into the phono ground or just snip them off. Its really not a issue either way. I didn't recieve your message till after 11 last night and didn't know if it was to late to call you. That preamp has many little tweaks like this that are not in the manual or on the schematic. Craig Link to comment Share on other sites More sharing options...
powdermnky007 Posted June 10, 2004 Author Share Posted June 10, 2004 Sounds good, I just didn't want to fry anything! I also noticed that when I move the preamp around I can hear something inside moving around. Is it just a loose wire, or is it something I should check out. Everything came in perfect, thanks for everything! Also do you have anything you've put together, like a walk through to bias the tubes on my dynaco poweramp? Do I ever need to check the tubes on the preamp? -Justin Link to comment Share on other sites More sharing options...
NOSValves Posted June 10, 2004 Share Posted June 10, 2004 If you open up the preamp you will find that it a so full of goodies that it will scare you ! yes some components will rattle if you shake it It will be fine just plug it in and enjoy !! Craig Link to comment Share on other sites More sharing options...
Dflip Posted June 10, 2004 Share Posted June 10, 2004 You should check the preamp tubes every hour on the hour for the first 10000 hours, or you could just leave them for the 5000 to 10000 hours that they should last. They last a long, long time. Craig's tubes are less than a year old, so they will be in very good shape. You will like the preamp, it works well and produces a nice sound. The other good thing is that Craig has burned in those Auricaps (they take 225-250 hours to burn in on the Mapletree). It is worth the wait. Good luck. Don Link to comment Share on other sites More sharing options...
NOSValves Posted June 10, 2004 Share Posted June 10, 2004 You didn't get a paper on how to bias the ST70 ? Craig Link to comment Share on other sites More sharing options...
powdermnky007 Posted June 12, 2004 Author Share Posted June 12, 2004 I may have, I will re-read the book I got on it one more time. It should be in there. Thanks, Justin Link to comment Share on other sites More sharing options...
NOSValves Posted June 13, 2004 Share Posted June 13, 2004 Justin, The factory Dynaco book is not the one to read if that is what you have ! I am back from Indy so if you want I can walk you through biasing the ST70 whenever you like on the phone. Craig Link to comment Share on other sites More sharing options...
Recommended Posts